US Census Fast Facts KION Here’s some background information about the census, a count of US residents that takes place every 10 years. The Census Bureau is part of the Department of Commerce. 2010 Census – US population – 308,745,538, a 9.7% increase from 2000 2000 Census – US population – 281,421,906 Other Facts The census is mandated by the US Constitution. “The actual enumeration shall be made within three years after the first meeting of the Congress of the United States, and within every subsequent term of 10 years, in such manner as they shall by Law direct.” – Article I, Section 2 of the Constitution of the United States. at a cost of $44,000. The population is estimated to be 3.9 million. Residents are categorized as free white males 16 years or older, free white males under 16, free white females, all other free persons and slaves.